1. Field of the Invention
This invention relates to wireless communication, and in particular, to use of an efficient beamforming protocol to support heterogeneous antenna systems based on millimeter-wave technology.
2. Description of the Related Technology
One of the major challenges for millimeter wave (mm-wave) gigabit per second (Gbps) communications is the poor link budget, as a radio signal propagating in the mm-wave frequency band experiences significant path loss, reflection loss and other degradation. Given the lossy nature of the radio channel as well as the limited CMOS performance at a mm-wave band, Gbps communications becomes very challenging. To improve the link quality, directional transmission is generally preferred.
Due to the extremely short wavelength, it becomes possible and beneficial to integrate a large number (e.g., between 10 and 64) of antenna elements into an antenna package. Antenna based beamforming thus emerges as an attractive solution, featuring high beamforming gain and electronic steerability. An improvement in signal-to-noise (S/N) ratio can be achieved by periodically performing antenna trainings in a beamforming wireless system.
In some communication systems (e.g., wireless communications systems using mm-wave frequency band), stations may use heterogeneous antenna types including single antenna, fixed sector antenna, switched beam antenna, and phase antenna arrays. Often, an initial step required in such networks is to perform a beamforming (direction antenna finding for optimal transmission and reception) between a station and a network coordinator station to enable high throughput data transmission at a later stage. Therefore, a need exists for an efficient beamforming protocol having a fixed beamforming period that can accommodate heterogeneous antennas with less protocol overhead.